1. Field of Invention
The present invention is related to electronic device test fixture component design and operation required during the test phase of electronic device manufacturing. More specifically, the present invention relates to the method and apparatus for the xe2x80x9cflexiblexe2x80x9d docking of a handler, containing a high performance contactor and device under test, with a test head, using dual xe2x80x9cOutriggerxe2x80x9d printed circuit boards electromechanically coupled to the test head via flexible supports reducing component stress and vibration.
2. Description of Related Art
Performance of final testing on packaged parts requires the electrical connection of two large electromechanical components, the ATE (automatic test equipment) test head and the device handler. Because of the large variety of testers and the large number of different package types, test heads and handlers come in a large variety of shapes and sizes. There are currently two methods used for coupling these two components, xe2x80x9chardxe2x80x9d docking and xe2x80x9csoftxe2x80x9d docking.
Hard docking requires the production of precise, often bulky, mechanical components to physically lock the handler to the test head. Typical components include the test head manipulator, test head docking plate, handler docking plate, alignment xe2x80x9cbarxe2x80x9d, guide pins, cam and/or vacuum lock to physically couple the test head to the handler. These items are expensive and often must be customized for each test head and handler type. Furthermore, setup requirements may result in extensive component changes when handler type A is switched to test head type B or handler type B is changed to test head type A.
In addition, every time test heads and handlers are docked, the mechanical alignment of the components needs to be checked. Although this prior art method results in a very secure connection of the two components and ensures high integrity signals to the device under test, the method has higher costs, skill and maintenance demands for production. The prior art method also exhibits poor visibility for components and difficult or expensive compatibility issues.
Another method used for coupling test heads and handlers is soft docking. In soft docking, the test head and the handler are connected by a simple male and female connector, usually a male edge-type connector on the handler and a female edge-type connector on the test head. Using the test head manipulator, the male and female connectors are joined by test floor operators after manually moving the components into alignment. The soft docking method benefits from low cost and simplicity, however the edge-type connectors often do not provide a high integrity AC signal path to the device under test, especially at frequencies above 10 MHz. In addition, since there is no mechanical connection between the test head and handler, any stresses in the soft docking process can result in damage or wear to the edge connectors and excessive stress on the mechanical assemblies which hold the connectors in place. This method is especially vulnerable to stress damage since there is nothing to take up the mechanical stress if the test head or handler is accidentally moved while the two components are docked.
Several flexible alignment solutions to these problems have been considered. In the prior art U.S. Pat. No. 5,828,223, issued Oct. 27, 1998 to Rabkin et al., vertical posts which allow a degree of float between a housing plate and loadboard are disclosed. In the prior art example however, the float between loadboard and housing plate is required to avoid disturbance to the test head when the chip handler is pneumatically clamped into place. The one-piece housing plate supported by the vertical posts as disclosed in the prior art is still much too rigid and fails to produce the flexible alignment and stress prevention required for docking and testing many devices. Stress on connectors in this prior art solution may actually be increased by the use of a one-piece plate in cases where alignments at one point may create misalignments at other points. Furthermore, the flex posts used to support the one-piece plate in the prior art lack any means to prevent overtravel between housing plate and loadboard. Connectors may be subject to damage unless alternate travel restrictions are used to limit the clamping force used to bring the components together.
Therefore what is needed is a method and apparatus to quickly and effectively dock the test head with a large variety of handler types while suppressing component stress damage. The new method should also achieve the best signal path possible between the test head and the device under test.
It is the object of the present invention to create a method and apparatus which may be used for the xe2x80x9cflexiblexe2x80x9d docking of a test head and handler which is broadly adapted to a large variety of test heads and handlers, allowing rapid and reliable setup changes for maximum production efficiency. In so doing, frequent and expensive setup changes may be eliminated or greatly reduced. In addition, another object of the present invention is a flexible docking method and apparatus which minimizes stress on components (and is therefore more xe2x80x9cproduction worthyxe2x80x9d) while achieving the best possible signal path between the test head and the device under test.
The present invention discloses a method and apparatus to achieve flexible docking while avoiding the expense of hard docking and many of the performance limitations of soft docking. Through the use of high-performance, high-integrity electrical connectors instead of edge-type connectors, and dual printed circuit board xe2x80x9cOutriggersxe2x80x9d capable of alignment through the use of flexible supports and offset guide pins, the present invention protects the high performance connectors and all mechanical components from damage during docking. Stress-free alignment of the dual Outriggers is accomplished through the use of a robust, inexpensive keyed guide pin system and flexible joints, which also absorb mechanical stresses preventing damage to sensitive mechanical and electrical components during testing.
With the present invention, no expensive hard docking components are required to couple test head and handler, and no hard docking compatibility issues exist. Because of the flexible joint, it is possible to dock a test head and handler that could not be docked with a hard docking solution without expensive mechanical modifications and additions, such as changing the test head manipulator. Relatively inexpensive components combine for a reliable, production worthy, docking solution.